The present invention relates to a system for a plate-shaped filter element in a gas filter housing, the filter element including filter material folded in a zigzag shape having filter folds closed at the front edges, and the closure being made essentially from the same material which forms the filter folds, and having an edge area projecting outward on both sides.
A plate-shaped filter insert for gas filters, which includes web material folded in a zigzag shape having filter folds closed at the front edges, is known from EP 0 490 169 B2. This filter insert has frame parts which are glued or welded onto the fold backs on the lateral areas of the filter insert formed by the fold front edges and project beyond the plate-shaped filter insert on all four sides so that this projecting area may be clamped tightly in the housing of a gas filter. The frame and the filter web may be made of an identical material or at least a material which has a similar composition. It has been shown to be disadvantageous in this case that either a prefinished strip-shaped frame or individual prefinished strip-shaped frame parts, which may be assembled into a frame, are to be attached to the web material folded in a zigzag shape.
A filter insert and a method for its manufacture, in which a folded pack made of a thermoplastic weldable nonwoven material is bonded along at least its two external sides to at least one seal in each case, is known from the document DE 195 32 436 C1. The seal, which is made of a thermoplastic weldable material, may be engaged with a filter housing enclosing the filter insert to form a seal. This is performed in that the sealing strips have a cross section folded in a V-shape, of which the first leg is bonded to the folded pack to form a seal and the second leg presses against the filter housing to form a seal due to its elastic pre-tension. Such a system, which is used in automobile internal filters, does not achieve the low leakage air rates required for the field of engine intake air area, which are lower than the required leakage air rate for automobile internal filters by a factor of three.